I'm having issues with consistent post-exercise headaches. Does anyone else have a problem with this? I get them almost every time after I run in the morning, but not after I run in the evening. (But maybe that's because I sleep soon afterwards.) I usually run before 8am in the morning, and by 1 or 2pm I start feeling a headache coming on. It's usually on one side of my head, and feels like a migraine.

I get migraines too, for other reasons... usually cigarette smoke, facial tension, or in the past I got them from aged cheese. One of the bonuses of becoming vegan has been fewer migraines, which is great, but I still seem to get the exercise-induced headaches.

I'm cooling down and stretching, drinking plenty of water, and replenishing carbohydrates during runs of over an hour, and within 15 minutes after every run.

Yes, I get exertion migraine headaches, too. I make sure I eat really well after exercise, have a good meal and you say you do eat well, which is good. Another thing I find helps is to have a sugary drink (i.e., a can of pop -specifically, I'll have a can of cola/Pepsi or better yet, a glass of the limeade recipe from Viva Vegan which has a lot of panela sugar) helps the headache. I find once my body gets used to the exertion, the headaches do go away (I usually get them if I worked especially hard or run in hot/humid conditions and hours after the exercise, as you say happens to you).

I used to get headaches last fall when I was running more than 4 or 5 miles at a time; in my case I'm almost positive they were dehydration-related. I would suspect that's at least part of the culprit here, since you're getting them in the morning - I read last week that we lose on average 750mL of liquid as we sleep, which is equal to a regular sized bottle of wine. That's a lot! So even if you are drinking plenty of water throughout the day, you might not be getting enough pre-run to make up for the deficit lost throughout the night.

I always eat something (usually carb-y) before working out in the morning, and try to have something to eat within an hour afterwards. I will try the sports drink after, to replenish magnesium or other electrolytes. I had a bottle of coconut water last weekend, which is supposed to be hydrating and rich in electrolytes, and I didn't get a headache. I also ate a pb sandwich afterwards, too. I am also trying to be more aware of the tension I hold in my face while I work out, and at other times of the day. I think this could be part of the cause.

I seem to be getting fewer headaches lately, after I started drinking a Vitamin Water after long runs. I usually chose a flavor with electrolytes, and not the Zero variety sweetened with Stevia, since I think it's the quick sugar that I need. This, plus drinking more water and eating a meal sooner, have probably helped.

I'd second the magnesium suggestion, along with a rehydration drink before and after exercise. I know exertion often worsens migraine (it certainly does for mine), I think it can be anything from increased blood flow to low blood sugar.